Which of the following commands checks for valid users on an SMTP server?

Question

Options

• ARCPT
• BCHK
• CVRFY
• DEXPN

• A
  4% (1)
• C
  93% (26)
• D
  4% (1)

Explanation

VRFY (Verify) is an SMTP command specifically designed to confirm whether a given username or email address is valid on a mail server. When sent to an SMTP server, VRFY asks the server to validate that the specified user exists, making it a common target for attackers performing user enumeration during reconnaissance.

Why the distractors are wrong:

• RCPT (Recipient) is used during the mail transaction process to specify the recipient of an email, not to verify user existence independently.
• CHK is not a valid or recognized SMTP command at all.
• EXPN (Expand) is a related SMTP command, but it is used to expand a mailing list alias to reveal all members, not to verify individual users.

Memory Tip: Think of VRFY = VeRiFY - the command literally does what it sounds like, verifying whether a user exists. If you can remember "VRFY = Verify a user," you'll never confuse it with EXPN, which expands a list.

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